Shopping Cart: Project set up & Login Screen

1) Create new project
Project is the collection of modules.

2) Create Modules
Module is the collection of facets.


3) There are lots of facets but 4 facets are quiet important to make a note of
Web, EJB, JPA and JEE facets.


4) Write a web.xml for your application in the web facet.


5) Configure an authenticator valve in context.xml


6) Write a redirect servlet

package com.shoppingcart.security.login;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.ServletException;
import javax.servlet.RequestDispatcher;
import java.io.IOException;
import java.util.Enumeration;


public class RedirectServlet extends HttpServlet
{
  protected void service(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse) throws ServletException, IOException
  {
      final String svlpath = httpServletRequest.getServletPath();
      Enumeration en = httpServletRequest.getAttributeNames();
      String actualReqPathKey = "javax.servlet.forward.servlet_path";
      String actualReqPath = (String)httpServletRequest.getAttribute(actualReqPathKey);

      String pageName = actualReqPath;

      if ("/unsecured/login".equals(svlpath)) {
          if("/index.jsp".equals(actualReqPath)) {
              pageName = "/Login.jsp";
          }
      }
      else {
          throw new ServletException("RedirectServlet: operation '" + svlpath + "' not supported!");
      }
      redirectToLogin(httpServletRequest, httpServletResponse, pageName);
  }

  private void redirectToLogin(HttpServletRequest request, HttpServletResponse response, String pageName) throws IOException, ServletException
  {
      RequestDispatcher dispatcher = this.getServletContext().getContext("/shoppingcart").getRequestDispatcher(pageName);
      if (dispatcher != null) {
          response.setContentType("text/html");
          dispatcher.include(request, response);
      }
  }

}

7) Mention about the module in application.xml


8) Configure JBoss from the ide.



9) Compile the application, deploy and run jboss.



How does it all work

When the user points the browser to localhost:8080/shoppingcart for the first time, the jboss server figures out from the web.xml configuration that this resource cannot be accessed publicly by everyone and that it needs to be secured and only allowed roles can access it. To authenticate the jboss server will use the FormAuthenticator which is configured as the valve in context.xml. The FormAuthenticator will interpret the request and changes the url to the one mentioned in web.xml, in this case it is /unsecured/login and redirects to RedirectServlet. The RedirectServlet will dispatch the request to Login.jsp and hence the Login.jsp is sent back to the browser.